Step 7: Wiring the Blimp

I have included some pictures of the wiring on mine, but it'll be a lot easier if you just go by the schematic.
I originally used a lot of heavy wiring and connectors in the name of neatness and convenience, but gave it up after I saw how much weight I had added. The result is a slightly tangled but very functional layout.

You should start by building your h-bridges -- if you haven't already, look at Mark Tilden's website for an excellent diagram. You'll probably want to build them on little boards so you can test them with your motors individually before soldering them in.

Once you've got those, you should start thinking about powering your circuits. I cut off the connector the battery came with -- you should too, it saves you 10 grams -- and replaced it with light wires ending in 0.1" sockets, so it can still be easily removed for charging. It plugs into pin headers that I soldered onto the through-hole board. I also put the 7805 on the board, so the power wires for the servo, radio, and Arduino originate from there. The two NPN transistors that the motors draw from (and that the Arduino PWM's ) are also in the board, with the "collector" pin connected directly to the 7.4V of the battery. Again, see the diagram.

Using the socket wires, I connected the Arduino to the h-bridges, radio, servo, and motor transistor. That green chip turned on its side is the TX module. The location for the h-bridges is pretty obvious -- one on either side of the servo. If you get the orientation of the motors wrong (for example, you push forward and it goes back), remember that it's really easy to change by swapping direction pins on the Arduino, or just by changing a line of code.
<p>Can something be sprayed onto a plastic wrap skin, to help hold in the hydrogen gas? I'm trying to keep it light, but don't want the gas to leak out too quickly. Really cool project.</p>
<p>Do you have any idea how much weight (gram) the blimp can lift ? </p><p>Thanks</p><p>Sam</p>
You blimp looks awesome, only the code is without any doubt the most incomprehensible code I have ever seen! I can't make heads or tails from it. Could you explain the how te code works? I really like the 433 MHz set I got, but I haven't found a clear code that I can adapt to my homemade rover. <br> <br>Thom
Darn, I have been trying to figure out your code for quite some time, IT-IS-SO-SIMPLE, I have tried to use virtualwire but then I can't use the servo library (they hate each other). Thanks for sharing it!
when I first read the title I accidently read &quot;Hydrogen bomb.&quot;
Nice work on this project! I had the same 433 Rx Tx units and could never get them to communicate properly! Definitely one of the best troubleshooting sections I've read!
this soo reminds me of the hindenburg. tho to be fair, hydrogen had nothing to do with the explosion. zinc paint(?!) was the problem. <br>very cool project. <br>tho 433mhz might not be legal in USA, but even a toy car with arduino could work
You are my hero. I have tried filling a smaller blimp with hydrogen in the same way, but using only very small amounts of lye (five attempts with no success). I would love to build a setup like this some day, especially one using a hydrogen fuel cell for power. One question: does the water buffer remove any steam or water vapor from the hydrogen entering the envelope? I always worried about getting water in it. Thanks for a very informative 'ible.
You're right to be worried about water vapor. It will only be a problem if you let the reaction get too hot, which will make it start steaming or even boil if it gets out of hand. If you make sure it doesn't get more than a little warm ( I dunno, 75 deg F), the water vapor will be negligible. If you're really worried about it, you could try running the gas through a percolator to cool it down before it enters the envelope (meaning some of the vapor would condense out). The buffer I have is mainly to prevent any water in liquid form that bubbles up from getting close to the envelope. Don't give up on lye!
Awesome. Love the chemistry lab details and the troubleshooting section.

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